Optimism and caution for an inactivated COVID-19 vaccine

Mathematical models indicate there will not be an adequate supply of vaccines available to cover the global population until 2023,5 further exacerbating health and other disparities in LMICs. [...]the early safety and immunogenicity results from Raches Ella and colleagues published in The Lancet Infectious Diseases6 of BBV152, a SARS-CoV-2 vaccine manufactured and produced in India by Bharat Biotech, are a welcome addition to the COVID-19 vaccine landscape. Despite these favourable phase 1 results, concerns linger regarding the potential for an inactivated whole-virus vaccine to elicit antibody-dependent enhancement of infection or vaccine-associated enhanced respiratory disease upon SARS-CoV-2 infection.7 Both of these effects are thought to be attributable to the development of binding, poorly neutralising antibodies that can promote either enhanced infection of Fc-bearing immune cells or immune complex deposition with T-helper-2 cell-biased allergic inflammation. The inactivated platform raises concern, because inactivation might alter antigenic structures and thereby elicit binding, non-neutralising antibodies. [...]achieving high titres of neutralising antibodies and T-helper-1 (Th1)-biased cellular responses are considered important safety metrics in the assessment of candidate vaccines.